Malibu V6-191 3.1L VIN M SFI (1997)
Torque Converter Clutch: Symptom Related Diagnostic Procedures
Noise - 4T40-E Transaxle
IMPORTANT: Do not confuse this noise with pump whine noise, which is usually noticeable in Park, Neutral, and all other gear ranges. Pump
whine will vary with line pressure.
You may notice a torque converter whine when the vehicle is stopped and the transaxle is in Drive or Reverse. This noise will increase as you increase
the engine RPM. The noise will stop when the vehicle is moving or when you apply the torque converter clutch, because both halves of the converter
are turning at the same speed.
Perform a stall test to make sure the noise is actually coming from the converter:
1. Place your foot on the brake.
2. Put the gear selector in Drive.
NOTICE: You may damage the transmission if you depress the accelerator for more than six seconds.
3. Depress the accelerator to approximately 1200 RPM for no more than six seconds. A torque converter noise will increase under this load.
Poor Acceleration at High Speed - 4T40-E Transaxle
If the stator is locked up at all times, performance is normal when accelerating from a standstill. Engine RPM and car speed are limited or restricted at
high speeds. Visual examination of the converter may reveal a blue color from overheating.
If the converter has been removed, you can check the stator roller clutch by inserting two fingers into the splined inner race of the roller clutch and trying
to turn the race in both directions. You should be able to freely turn the inner race clockwise, but you should have difficulty in moving the inner race
counterclockwise or you may be unable to move the race at all.
Poor Acceleration at Low Speed - 4T40-E Transaxle
If the stator is freewheeling at all times, the car tends to have poor acceleration from a standstill. At speeds above 50-55 km/h (30-35 mph), the car may
act normally.
For poor acceleration, you should first determine that the exhaust system is not blocked, and the transmission is in First gear when starting out.
If the engine freely accelerates to high RPM in Neutral, you can assume that the engine and the exhaust system are normal. Check for poor performance
in Drive and Reverse to help determine if the stator is freewheeling at all times.
General Information
The key to diagnosing Torque Converter Clutch (TCC) shudder is to note when it happens and under what conditions.
TCC shudder which is caused by the transmission should only occur during the apply or the release of the converter clutch. Shudder should seldom occur
after the TCC plate is fully applied.
If Shudder Occurs While TCC Is Applying or Releasing
If the shudder occurs while the TCC is applying, the problem can be within the transmission or the torque converter. Something is causing one of the
following conditions to occur:
-
Something is not allowing the clutch to become fully engaged.
-
Something is not allowing the clutch to release.
-
The clutch is releasing and applying at the same time.
One of the following conditions may be causing the problem to occur:
-
Leaking turbine shaft seals.
-
A restricted release orifice.
-
A distorted clutch or housing surface due to long converter bolts.
-
Defective friction material on the TCC plate.
If Shudder Occurs After TCC Has Applied
If shudder occurs after the TCC has applied, most of the time there is nothing wrong with the transmission!
As mentioned above, the TCC is not likely to slip after the TCC has been applied. Engine problems may go unnoticed under light throttle and load, but
they become noticeable after the TCC apply when going up a hill or accelerating. This is due to the mechanical coupling between the engine and the
transmission.
Once TCC is applied, there is no torque converter (fluid coupling) assistance. Engine or driveling vibrations could be unnoticeable before TCC
